电解锰废水中Cr6+、Mn2+的去除方法研究

通过实验研究了还原沉淀-晶种曝气组合工艺去除电解锰废水中Cr6+和Mn2+，并探索了最佳工艺条件.首先以Na₂SO₃做还原剂将Cr6+转化为Cr3+后再通过化学沉淀法除去，然后采用加入MnO₂做晶种曝气氧化去除废水中的Mn2+.结果表明:当Na₂SO₃投加量为0.5 g/L，还原反应pH值为4，还原反应时间6 min，Cr6+可完全转化为Cr3+.Cr3+在pH值为8时沉淀最完全，出水总铬浓度可从100 mg/L降到0.5 mg/L以下.除铬后，当MnO₂投加量为25 g/L，废水pH值为9，曝气10 min，出水Mn2+浓度可从1 000 mg/L降到0.4 mg/L以下.通过以上处理出水总铬和总锰均达到我国《污水综合排放标准（GB8978-1996）》一级要求. 

Removal of Cr6+and Mn2+from electrolytic manganese wastewater

A new technology of reduction precipitation combined with crystal seed aeration is proposed for completely removing Cr6+and Mn2+ from electrolytic manganese wastewater by studying the optimum treatment conditions.In the first step, Cr6+was removed by chemical precipitation by transforming into Cr3+using Na₂SO₃ as reductant.Then Mn2+ is removed by aeration using MnO₂ as crystal seed.The results are as follows: Cr6+can be transformed into Cr3+completely with Na₂SO₃ dosage of 0.5 g/L, reduction pH value of 4, reduction time of 6 min.Precipitation of Cr3+is the most complete when pH value is 8 and the effluent concentration of total chromium is less than 0.5 mg/L from 100 mg/L.After chromium removal, the effluent concentration of Mn2+ is less than 0.4 mg/L from 1 000 mg/L when MnO2 dosage is 25 g/L, wastewater pH value is 9 and aeration time is 10 min which meets the first grade national sewage effluent discharge standard (GB8978-1996).